This invention relates to the field of large video display systems of the type appropriate for installation at a stadium. Such displays are usually formed by a large matrix of variable intensity display devices as, for example, incandescent bulbs, which are driven by a display system usually computer controlled. The display system receives a video input, such as the line feed from a network broadcast or a video tape recording and digitizes the video information into a complete frame of digital data. In prior systems the digitized data was stored in a computer memory and then at an appropriate point transferred from memory to the display device. Computers utilized for such a system include the Digital Equipment Corporation PDP Series 8. Although such mini computers are relatively powerful devices, their data transfer rate, as compared in random access memories, is low. As a result the computer represents a limiting element in the system with respect to the rate at which data can be digitized and transferred to the display device thereby limiting the versatility of the system with respect to other desirable features, such as maintaining statistics on participants, displaying caricatures, cartoons, or still photographs of the players.
It is therefore a desirable objective to retain computer control of the display system but to remove the computer from the data path to the display board. The PDP computer referred to employs data break cycles to transmit information to the display board. It does not have time to do the other tasks as mentioned, such as disk storage input and output, statistical updating and message inputting in addition to refreshing the display. Furthermore, when the computer is included in the data path it is necessary to synchronize the computer to the master clock. This slows down processor time still further.
It is accordingly an object of the present invention to provide a display system which is capable of higher speed than prior devices by virtue of removing the computer from the data path. By so doing the computer is able to perform a variety of other tasks as indicated. More importantly, it is possible to obtain a heretofore unavailable display in which a portion of the video picture being displayed can be enlarged to permit better viewing thereof. Often this is analogized to "zooming" in the manner permitted by an adjustable lens in photography. To obtain an enlarged or zoom picture it is necessary to utilize greater data rates than present systems can handle. The present invention, by removing the computer from the data path, is capable of operating at these higher data rates.
Exemplary of prior systems for displaying data on large display devices are U.S. Pat. Nos. 4,009,335, 3,941,926, and 3,961,365 assigned to the assignee of the present invention.